1. Field of the Invention
The present invention relates generally to plasma display panels without injection tips and methods of manufacturing the same, and more particularly, to a plasma display panel without any injection tip and a method of manufacturing the same, which has a structure capable of injecting gas into and sealing the thin plasma display panel, without using any injection tip, while manufacturing the thin plasma display panel, thus stably exhausting air from and injecting the gas into the plasma display panel, reducing a space required to install the plasma display panel in a frame of a neon sign, and avoiding damages, caused by the injection tip of a conventional plasma display panel, while carrying the plasma display panel.
2. Description of the Related Art
Generally, neon signs are light emitting devices to display letters or pictures (hereinafter, term “advertisement pattern” is used to include all of the designs, such as letters, logos and etc., for an advertisement) for the purpose of advertising.
In the conventional neon signs, a heated glass tube is deformed into a predetermined shape. Thereafter, electric-discharge gas, such as neon or etc., is injected into the glass tube, thus forming a desired advertisement pattern.
That is, the glass tube has been used to form the advertisement pattern, such as letters or marks to be advertised. However, the conventional glass tube is supported by a support frame in the neon signs. Therefore, the conventional neon sign using the glass tube is problematic in that its size is excessively increased.
In addition to the above-mentioned problem of increasing the size, the conventional neon sign is easily broken by an external force due to structural fragility of the glass tube. Furthermore, because a voltage more than 1 KV is used as a main power supply, an accident of electric shock may be undesirably caused.
In addition, to deform the conventional glass tube having a predetermined diameter, a part of the glass tube is heated to obtain a partially melted state. Thereafter, the glass tube is bent into a predetermined shape, thus forming the desired advertisement pattern.
Therefore, the advertisement pattern, which is represented by the glass tube used in the conventional neon sign, must be limited due to the predetermined diameter of the glass tube. That is, it is almost impossible to form a letter or a pattern of a size smaller than the predetermined diameter of the conventional glass tube. A size of the letter or pattern represented by the conventional glass tube is also limited.
In an effort to overcome the problems experienced in the conventional neon signs using the glass tubes, a luminous sign board was disclosed in U.S. Pat. No. 4,703,574. Although the luminous sign board disclosed in U.S. Pat. No. 4,703,574 provides a luminous sign board with a planar board shape, its structure is complex.
That is, to manufacture the conventional luminous sign board disclosed in U.S. Pat. No. 4,703,574, three sheets of plate material, which are a front transparent legend plate, a center feedthrough plate and a back crossover cavity plate, are provided. The three sheets are coupled to each other, so that a cavity is selectively provided between the three sheets to define a desired letter and pattern. In the above state, discharge electricity is induced in the cavity, thus representing the desired letter and pattern.
As such, the structure of the conventional luminous sign board disclosed in U.S. Pat. No. 4,703,574 is complex. Furthermore, because the conventional luminous sign board uses a back light source which is an indirect illumination technique, the fluorescent color of neon is deteriorated.
To solve the above-mentioned problems experienced in the conventional luminous sign, a neon sign device was proposed in Korean Patent Registration NO. 312613 (entitled: Neon sign device having plain shape and method for manufacturing the same). The conventional neon sign device disclosed in NO. 312613 has a thin construction in comparison with the conventional luminous sign board disclosed in U.S. Pat. No. 4,703,574. That is, the conventional neon sign device of NO. 312613 has a simple structure, thus reducing its size. Furthermore, the conventional neon sign device of NO. 312613 has the structure possible to represent finer letters and marks, withstand external forces, and prevent the electric shock from being undesirably caused.
The conventional neon sign device (hereinafter referred to as electric sign board) includes an upper glass substrate, with an electric discharge electrode provided on a lower surface of the upper glass substrate. The conventional electric sign board further includes a lower glass substrate which is attached to the lower surface of the upper glass substrate, with an electric discharge space to represent a predetermined advertisement pattern into a cavity.
That is, a basic technical spirit of the conventional electric sign board disclosed in NO. 312613 is that the electric discharge space is defined between the lower glass substrate and the upper glass substrate, so that electric discharge is generated in the electric discharge space using the electric discharge electrode which is a transparent electrode. The conventional electric sign board is a device of a P.D.P (plasma display panel) type, different from an LCD (liquid crystal display), which is a flat panel display. The conventional electric sign board has therein a fluorescent material and inert gas, so that the electric discharge is generated through the transparent electrode by discharge electricity.
As shown in FIGS. 1 and 2, the fluorescent material 2b is applied to a surface of the cavity 2a. Inert discharge gas G is injected into the cavity 2a. The cavity 2a is engraved on a predetermined portion of an upper surface of the lower glass substrate 2, for example, by an etching process.
The electric discharge electrode of the conventional electric sign board 10 comprises two transparent electrodes 1-1 and 2-1 and bus electrodes to supply the discharge electricity to the two transparent electrodes 1-1 and 2-1.
Referring to FIG. 3, a method of manufacturing the conventional electric sign board 10 having the plain shape includes step 100 of forming the electric discharge electrode on the upper glass substrate 1, and step 200 of forming on the lower glass substrate 2 the cavity 2a having a role as the electric discharge space and corresponding to the advertisement pattern. The method of manufacturing the conventional electric sign board 10 further includes step 300 of coupling the upper glass substrate 1 and the lower glass substrate 2 to each other.
Step 300 includes a providing an injection tip T which is made of a glass tube and communicates with the cavity 2a defined between the upper glass substrate 1 and the lower glass substrate 2 that are closely bonded together at step 302. The injection tip T is mounted on either side of the upper glass substrate 1 and the lower glass substrate 2. Preferably, the injection tip T is mounted on the lower glass substrate 2.
Substantially, the injection tip T is made integrally when the upper glass substrate 1 and the lower glass substrate 2 are attached to each other.
Step 300 further includes step 304 of injecting both the electric discharge gas and getter, which is high oxidative material and will be described later herein (in step 306), into the cavity 2a through the injection tip T.
For example, mixed gas of neon, zeon and helium can be injected to the cavity 24.
The mixed gas does not substantially give out any color upon electric discharge. When only ultraviolet rays are emitted by the electric discharge, the ultraviolet rays illuminate the fluorescent material coated and baked on the cavity 2a. 
In the meantime, in step 304, after injecting a specific gas into the cavity 2a, the injection tip T to inject the gas into the cavity 2a is tipped off, as shown in FIG. 2.
Thereafter, the opened injection tip T is sealed through a melting process, thus maintaining the vacuum in the cavity 2a. In practice, to exhaust air from and inject the gas into the cavity 2a, the process of sealing the injection tip T is accomplished by melting and clogging both the injection tip T and a tubular body T1 in state in that the tubular body T1 is coupled to the injection tip T.
Thereafter, the completed conventional electric sign board 10 having the plain shape is assembled with its peripheral components before being practically mounted indoors or outdoors.
After the conventional electric sign board 10 is completed through the above-mentioned manufacturing process, an electrical current is applied to the electric discharge electrodes 1-1 and 2-1 to generate electric discharge between the electric discharge electrodes 1-1 and 2-1 which are exposed to each other.
By the ultraviolet rays emitted by the electric discharge, the fluorescent material 2b, which is applied on the surface of the cavity 2a, illuminates the advertisement pattern, such as letters or logos, defined by the cavity. Thus, a desired advertising effect is obtained.
However, in the conventional electric sign board 10 manufactured by the above-mentioned method, the injection tip T, which is made of the glass tube and communicates with the cavity 2a defined between the upper glass substrate 1 and the lower glass substrate 2 to inject the gas into the cavity 2a for the electric discharge, has following several problems.
First, the injection tip T, which is made of the same glass material as the lower glass substrate 2, is mounted to the lower glass substrate 2. Therefore, during the process of exhausting air from and injecting the gas into the cavity 2a, the injection tip T may be broken by interfering with a gas injection apparatus. In addition, after completing the process of injecting the gas into the cavity 2a, the injection tip T may be broken during the process of sealing the injection tip T or carrying the electric sign board 10.
As described above, the process of sealing the injection tip T is accomplished by melting the injection tip T and tipping off an unnecessary part from the injection tip T (at a melted portion of the injection tip T). At this time, a remaining part of the injection tip T is always projected from the lower surface of the lower glass substrate 2. Therefore, when the conventional electric sign board 10 along with other components is installed at a predetermined position, a space required to install the conventional electric sign board 10 is unexpectedly increased due to the projected part of the injection tip T. That is, the conventional electric sign board 10 with the injection tip T is limited in its installation space.